Apparatus and methods are known to identify tumorous masses suspected of being malignant, for example, by radiographic and sonographic techniques. It is typical for such tissue masses to then be biopsied to determine status as, or degree of, malignancy, to determine further course of treatment. For example, a region of a mammogram suspected to contain a lesion may be biopsied to determine whether the lesion is benign or malignant, and if malignant, the course of treatment appropriate for the degree of malignancy, e.g. mastectomy, radiation treatment or chemotherapy.
Previously known biopsy methods range from minimally invasive techniques, such as fine needle aspiration using a 21 gauge hypodermic needle and large core biopsy using a 14 gauge needle mounted in an automated biopsy gun, to open-procedures in which the lesion is surgically excised. Minimally invasive techniques are faster, less expensive, safer and less traumatic for the patient than surgical excision, and begun developing widespread acceptance.
A concern common to previously known minimally invasive biopsy techniques, however, is ensuring that the biopsy needle actually obtains a tissue sample from the suspected lesion, rather than adjacent healthy tissue. Previously known techniques that attempt to ensure that the biopsy needle trajectory enters the region of the suspected lesion are described, for example, in Fornage et al., "Ultrasound-Guided Needle Biopsy Of The Breast And Other Interventional Procedures," Radiologic Clinics Of North America, Vol. 30, No. 1 (January 1992), Fornage et al. "Breast Masses: US-Guided Fine Needle Aspiration Biopsy," Radiology, 162:409-414 (February 1987), Parker et al., "US-guided Automated Large-Core Breast Biopsy," Radiology, 187:507-511 (May 1993), and Parker and Jobe, "Large-Core Breast Biopsy Offers Reliable Diagnosis," reprinted from Diagnostic Imaging (October 1990).
The foregoing articles describe a free-hand ultrasound technique, in which insertion of a biopsy needle into a suspected lesion is performed by holding a linear array ultrasound transducer in one hand and inserting the needle into the tissue with the other hand. In particular, the ultrasound transducer is held above the midline of the suspicious mass and the needle (or needle of the automated biopsy gun) is then inserted in the tissue near the base of the transducer, so that the tip of the needle appears in the ultrasound scan. In addition, when a biopsy gun is employed, additional personnel may be required to steady the biopsy gun during use or to hold the ultrasound transducer.
As described in the Fornage et al. articles and Parker et al. article, difficulties arise using the free-hand technique where the suspected lesion is located near the patient's chest wall, or in proximity to a prothesis. These articles also emphasize that the practitioner's level of skill in using the free-hand technique can dramatically influence the results obtained. All of the foregoing articles reject the use of biopsy needle guides that can be attached to the ultrasound transducer, because the guides interfere with the flexibility and maneuverability required to obtain satisfactory results.
The Parker and Jobe article also describes stereotactic mammographic biopsy systems. In such systems, two X-ray images of the breast tissue are made at different angles, thereby permitting the coordinates of a lesion to be calculated. The biopsy needle, typically an automated biopsy gun (e.g., Biopty from C. R. Bard, Inc., Bard Urological Division, Covington, Ga.) mounted in a rigid housing attached to the biopsy table, is moved to the calculated coordinates and actuated. Two additional X-ray views of the breast tissue are then taken to confirm that the needle has actually sampled the region of the suspected lesion.
The Parker and Jobe article further describes the drawbacks of add-on stereotactic systems--namely, the potential for breast movement that renders earlier stereo calculations worthless. That article also describes the Mammotest system sold by Fischer Imaging Corporation, Thornton, Colo., as overcoming some of the problems of add-on stereotactic systems, but at a considerable cost differential.
A drawback common to all of the stereotactic systems, however, is the need for multiple X-rays of the tissue, thus exposing the tissue to potentially unhealthful ionizing radiation. These systems also provide no real-time imaging of the needle trajectory, so as described in the Parker and Jobe article, intervening movement of the breast tissue may render the calculated coordinates useless and result in a potentially misleading biopsy sample. Indeed, the clinician is not even aware that the biopsy needle missed the intended target until after the follow-up stereotactic views are taken.
Moreover, because the biopsy needle is secured in a fixed housing so as to provide a fixed trajectory for biopsy needle, stereotactic systems provide no freedom of movement for the biopsy needle relative to the target tissue. Consequently, several needle insertions and withdrawals are required to adequately characterize the tissue.
A major disadvantage of the above-described previously known methods and apparatus arises due to the inability of the clinician to estimate, in real-time, the correct trajectory of the biopsy needle from the breast surface to the region of the suspected tumor or lesion. Even when guided by free-hand ultrasound scanning, the clinician typically must insert and withdraw the biopsy needle ten to fifteen times or more to improve the confidence level that a portion of the suspected lesion has been collected. Then, each of the needle aspiration samples must be separately tested, significantly increasing the overall cost of the procedure.
Likewise, in stereotactic systems, the inability to monitor tissue movement and to manipulate the biopsy needle once inserted, creates the need for multiple needle insertions to obtain adequate characterization of the suspected lesion. And again, each of these multiple samples must be individually tested to properly characterize the suspected lesion.
Such repetitive insertion and withdrawal of the biopsy needle may cause significant patient discomfort. Moreover, in those cases where the biopsy indicates no need for treatment by surgical methods, the repeated biopsy needle insertion may nevertheless leave the patient with cosmetically unappealing scar tissue.
A further disadvantage of these previously known methods and apparatus is the potential for seeding the needle tracks with potentially malignant tumor cells. For example, because the clinician in previously known methods must make several needle insertions to confirm that he or she has sampled cells from the target tissue, there is the potential that malignant cells may be dispersed along a needle track which was not believed by the clinician to have entered the region of the suspected tumor, but which in fact did so.
In view of the foregoing, it would be desirable to provide apparatus and methods by which a biopsy needle could be positioned for insertion so as to have a real-time, predetermined trajectory to a targeted tissue region, thereby reducing the need for repetitive needle insertion and withdrawal to obtain a biopsy sample.
It would also be desirable to provide apparatus and methods by which a biopsy needle could be positioned for insertion in real-time with a high degree of confidence that the needle trajectory will enter a targeted tissue region, thus reducing the risk of spreading potential malignant tumor cells by dispersing them along multiple needle tracks.
It would also be desirable to provide apparatus and methods by which a biopsy needle could be positioned for insertion into tissue along a predetermined trajectory, and which enables the clinician to alter that trajectory once the needle has been inserted, so as to reduce the number of scars resulting from repetitive skin punctures.
A yet further drawback of previously known biopsy systems, including those employing ultrasonic imaging of the biological tissue, is the inability to assess tissue features located near, or extending within, the chest wall. Such features typically have been inaccessible to previously known radiographic and sonographic imaging techniques due to the inability, for example, to direct such X-radiation to the X-ray film, while in sonographic systems, complicated structures including submersing the tissue in a water bath have been required.
It therefore would be desirable to provide a biopsy system having enhanced imaging capability to provide images of biological features located near or within a patient's chest line.